1. Field of the Invention
The present invention generally relates to the field of tooling assemblies used in automatic or computer controlled machine tools and more particularly to devices for inserting and removing retention knobs from said tooling assemblies.
2. Description of the Prior Art
Automatic or computer controlled machine tools are characterized by having a multiplicity of individual tool holding assemblies which can be individually accessed and used for particular drilling, cutting, turning or threading operations. Typically, these assemblies comprise a keyless chuck having a vertical hollow shaft running its entire length. At the bottom end or base it is adapted to receive and fixedly hold a working tool in proper orientation to perform a particular metal-working function. The opposite distal end of the shaft is threaded and adapted to receive and threadably hold a retention or "pull stud" knob. Normal practice is to store a number of these tool assemblies in a tool rack, with the end of the chuck holding the working tool bit oriented downwardly and the retention knob oriented upwardly. Whenever a particular tool assembly is needed, a control signal generated by the computer causes a gripper to be dispatched to its location within the tool rack, then to firmly grasp the tool and then finally to remove the tool from the rack for subsequent use in the machine. At the conclusion of the machining operation, the above movement is reversed so that the working tool assembly is removed from the working area and returned to it's tool rack position for storage until needed again.
While a small machine shop may have only one computer controlled machine, most larger captive in-house and outside commercial shops will have several. Further, these several units, which are usually made by different manufacturers, may differ significantly in age, overall function and in the design and capacity of the ancillary equipment, such as the tool rack and the tool assembly gripper. Because the tool racks associated with each of these units are usually limited in the number of tools they can hold, it may be necessary to move one or more particular tool assemblies from one machine to another to accomplish a particular task. Although the cutting tools and the keyless chucks holding them are more-or-less standard and universal in use, the designs associated with different machines, while similar in function, usually differ somewhat in form. These machines usually require a particular retention knob style so that the tool assembly may be properly moved into the correct position within the machine. Consequently, tooling assemblies set up for use in one manufacturer's machine tools may not properly fit into another manufacturer's equipment unless the retention knob is removed and replaced with one specifically adapted to work with that machine.
Retention knobs for each different machine design are similar in function, but they are usually found to differ in form in that some are relatively short while others are much longer. To facilitate their removal and reinstallation, most retention knobs typically have a narrow pair of diametrically opposed flat lands so that one can use a wrench or similar tool to grip these lands so that the knob can be rotated either for removal from the chuck or for installation therein. Since these opposed lands are relatively small, a normally sized wrench may be used only with some difficulty when one desires to first grasp these lands and then hold the knob while it is being inserted into or removed from the chuck body, without experiencing some amount of slippage and subsequent damage to the lands. Also, retention knobs are sometimes placed into the chuck body by an assembly machine and when this is done, they are usually tightly bound therein. Most often they are manually installed and usually over-tightened to be sure that they are firmly seated. Regardless of the method used to install these knobs, this tight fit, when combined with the normal stresses introduced during the machining operation, and the small amount of corrosion which may be experienced in normal operation means that loosening and then unscrewing them often requires a fairly intensive initial turning force. Consequently, the use of a standard box or adjustable end wrench may place uneven stresses on the knob body, particularly the gripping points and the threads holding the knob in place within the chuck body. After a while, the cumulative damage caused by using a wrench will degrade the retention knob to the point where it cannot be used further and must be discarded. Since retention knobs are typically made of hardened steel and are, therefore, relatively expensive, it is obvious that a less damaging means for changing them would result in a significant cost saving for the average machine shop.